Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
  • G01N27/68—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using electric discharge to ionise a gas
  • G01N27/70—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using electric discharge to ionise a gas and measuring current or voltage
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/0078—Testing material properties on manufactured objects
  • G01N33/0081—Containers; Packages; Bottles

Definitions

• the present invention relates to a method for determining a measured quantity of gas from an empty or partially empty container according to the preamble of claim 1, a measuring system according to that of claim 16 and a use of the method.
• EP-A-0 306 307 which is hereby declared to be an integral part of the present description, it is known to detect empty containers, in particular plastic containers, such as plastic bottles, as part of the container recycling - Check whether there is any contamination inside the container.
• ionization technology such as flame ionization or photoionization in the UV range, to detect the contaminations mentioned and, if appropriate, to contaminate contaminated containers before refilling, with preference given to UV photoionization.
• EP-A-0 306 307 The ionization technique known and preferred in EP-A-0 306 307, namely by means of UV light, is complicated. For this purpose, reference can be made to the statements in the above-mentioned EP itself, according to which the ionization device frequently has to be cleaned. In addition, the necessary UV lamps are expensive. Nevertheless, UV photo ionization is preferred.
• the present invention aims to propose a method of the type specified in the preamble of claim 1, by means of which the disadvantages of the technology according to EP-A-0 306 307 are eliminated.
• an electrical discharge gap for example similar to an internal combustion engine spark plug, is extremely simple, since such a miniaturization can be miniaturized, is not susceptible to contamination and, flexibly, can be supplied electrically practically anywhere.
• the use of electrical discharge paths for gas ionization has been known for a long time, for example from
• the procedure according to the invention is very fast because it is essentially independent of the flow rate of the gas and because, in contrast to flame ionization, it can be used in the container itself in certain applications.
• FIG. 3 schematically shows the use of a spark gap according to the invention for ionizing the storage gas in the container itself
• FIG. 4 schematically shows a first embodiment variant for discharge ionization of the gas and subsequent electrostatic ion deposition to determine a measurement variable, 5, in analogy to the representation of FIG. 4, a further training in which deposits are recorded as measured variables depending on the respective ion mobility.
• a spark ionization device with, downstream, an electrostatic mobility-selective ion separation device
• FIG. 7 shows schematically the provision of a preselection to prevent explosions in the case of certain contaminants, in the case of a discharge path in (a) or outside (b) of the container,
• FIG. 8 schematically, on a measuring system according to the invention, a conveying device for containers occurring in a stream and a gas extraction device, connected upstream of the measuring arrangement according to the invention with a discharge path.
• the present invention relates to the problem of examining the contamination state, in particular in the case of empty containers.
• empty containers For example, in the case of plastic bottles that occur in a stream to be recycled, there is great uncertainty as to how they were used after their emptying from their original filling, such as mineral water, fruit juices, etc.
• bottles are for example in households, often used in a different way, for example for storing soapy water, crop protection agents, motor oil, acids, petrol, petrol etc.
• FIG. 1 schematically shows a first embodiment variant of a device for determining a measured variable, at least co-significant for whether contaminants of a certain group of substances are contained in the gas contained in an empty container. are or are not. Since the filling material for a container can also be contaminated in certain cases and the gas above it is then contaminated, the method according to the invention can also be used on containers that have already been filled.
• a sampling line 1 is used to extract a gas sample G from an empty or partially filled container, not shown here, to be checked, as shown schematically in FIG. 8, and possibly also outside the container, with or with its contents directly in contact, sucked out and guided past a discharge path 3 with a pair of electrodes 5.
• the route 3 is operated by means of a current source 7.
• the discharge is generated as a corona discharge or as a spark discharge.
• the output signal of the voltage measuring device 11 is evaluated as a measurement variable and for this purpose is fed to a comparator unit 13, which is further supplied with reference signals from a reference signal unit 15. Depending on the discharge voltage U
• F niert, output signals A, A ... are output as measured values that are relevant for certain sub-groups of contaminants or even certain contaminants or for certain contaminants concentration.
• the reference signals are determined by calibration measurements and set using standardized, contaminated gas samples.
• FIG. 2 Based on the representation according to FIG. 1, a further measurement variable determination is shown in FIG. 2 on a discharge path 3 provided according to the invention.
• the discharge is maintained here by a controllable high-voltage source 7a, between the electrodes 5 of the spark gap 3.
• the discharge current i is measured on a current measuring device 11a
• Reference signal unit 19 adjustable current reference value i compared.
• the difference signal __ determined at the comparator unit 17! is carried out as a control difference, possibly via a controller 21, as a manipulated variable to the controllable voltage source 7a, which now acts as an actuator in the current control loop, such that the discharge current i at the reference signal source 19 as
• F setpoint generator follows adjustable reference value, preferably corresponds to the constantly set reference value i. SHOULD
• Control signal s for the voltage source and / or the u output voltage of the voltage source 7a is evaluated as a measurement variable.
• this measurement variable can in turn be fed to a comparator unit 13 with an upstream reference signal unit 15, and depending on the signal range in which the one determined on the control loop Measured variable is concluded, the presence or absence of contaminations of different groups of substances or the presence of contaminations of different concentrations in the gas sample G is concluded.
• the discharge behavior of the discharge path 3 and its electrical control, and consequently the discharge path itself, is used directly as a measurement sensor for the measured variable.
• a corona AC or DC discharge is generated.
• the gas sample G can be removed via an extraction line 1 in accordance with the respective container to be checked.
• the discharge path 3 can be miniaturized easily, e.g. With the aid of a test lance 23 shown schematically in FIG. 3, the discharge path 3a is driven into the respective container 25 to be checked and then proceed according to the explanations from FIGS. 1 and 2.
• the taps 27 on the lance 23 according to FIG. 3 correspond to the taps on the discharge paths 3 shown there in FIGS. 1 and 2 with the same position number 27.
• FIG. 4 shows a further embodiment of an Arrangement according to the invention for carrying out the procedure according to the invention is shown, in which the gas is ionized by means of the discharge path and, in contrast to the variants according to FIGS. 1 and 2, the ionized gas is examined separated from the discharge path.
• the gas sample G is taken from the respective container to be checked or its immediate surroundings via the removal line 1 and is supplied to the discharge path 3, operated with the current source 7.
• a capacitor arrangement for example a cylinder capacitor 29, is provided downstream of the discharge path 3 in the gas flow direction. It comprises the cylindrical outer capacitor jacket 29a and the coaxial inner mandrel 29i.
• the capacitor 29 is charged to a predetermined voltage value via an adjustable voltage source 31, which forms an electric field E on the capacitor. Due to the gas ionization at the discharge path 3, depending on the polarity and strength of the electric field E, ions of one polarity are driven to one of the capacitor plates 29a, 29i, ions of the other polarity to the other. The balance of the ions driven to the capacitance plates 29a, 29i results in a current i in the outer circuit connected to the cylinder capacitor 29 as an ion separator. This is measured as Strominte ⁇ gral with a charge amplifier 32 • or, as shown in phantom, ker with a Stromverstär ⁇ 32a.
• the integration time T during which the current flowing through the capacitor 29 is integrated is specified, this time period T being triggered by any signal ST defining the start of the measurement cycle, for example at Start of gas extraction or when a defined rising edge of the current i.
• the output signal is fed to a comparator unit 13 in the manner already described with reference to FIG. 1, on the output side, selected according to the size of the initial ⁇ input signals E, output signals A, A etc.
• the spark gap 3 provided according to the invention, be it, according to FIG. 3, in a container to be checked itself, or, as shown in FIG. 4, be arranged in the extraction line 1, for ionizing the gas to be checked .
• This procedure allows the gas ionization to be provided in a structurally flexible manner at any location of a selection system thanks to the miniaturization of the spark gap.
• the deposition takes place in the same place, be it along the extraction line or be it in the container to be monitored itself, carried out or locally separated from the ionization.
• the ionized gas G * is fed to an electrostatic separator stage 35 constructed essentially according to FIG. 4, which again consists, for example, of a cylinder capacitor arrangement.
• the gas with ions of different mobility enters the condensate gate space 30z and experience therein due to the homogeneous field strength E, the same charges of the ions are exposed, and the same deflection forces, more mobile ions are deflected more per axially traveled distance than less mobile ones.
• the currents i, i ... discharged from the respective capacitors are thus a measure of the
• the tapped currents i are each detected, as explained with reference to FIG. 4, via charge amplifiers or current amplifiers and processed further as measurement variables for the container selection.
• FIG. 6 shows an embodiment for discharge ionization of the gas and electrostatic deposition measurement, directly in a respective case.
• a plurality of mutually insulated metallic surfaces 33i and, coaxially with it, a metallic cylindrical surface 33a are provided on the lance 23 with a discharge path 3 at the end.
• the lance developed in this way is let into a respective container to be tested and the gas is ionized in the bottom region thereof by means of the discharge path 3.
• the gas is ionized in the bottom region thereof by means of the discharge path 3.
• the separator stage formed by the capacitors 33i, 33a lies.
• the flow of the ionized gas G * is also enforced by injecting a further gas, as shown by schematically illustrated openings 37.
• a corona discharge is preferably generated in the embodiment variants according to FIGS. 1 to 3. 4 to 6, both a corona discharge and a spark discharge can be generated, that is, when the ionization of the gas is measured.
• a series of a predetermined number of sparks is preferably generated for a measurement and the ion density is measured in the flowing, thereby ionized gas G * and averaged over a predetermined time in order to obtain more meaningful results.
• semiconductor gas sensors or electrochemical cells are preferably used, coordinated with the detection of known explosive contaminations. If a container with explosive contamination is detected, the corresponding container is excreted from the further check, as shown schematically, for example by setting a conveyor switch. Containers which are harmless in this regard are fed to the ionization measuring station 42 with a lance 23.
• a further conveyor switch is set and inadmissibly contaminated containers are removed or are subjected to a special cleaning, while containers contaminated with contaminations of the permissible type are supplied for refilling.
• any contaminants absorbed into the wall of the container before the contamination detection is carried out is carried out.
• this is done by heating the containers, as shown by the heat flow Q, which can be done by infrared radiation, in the case of plastic containers in particular also by microwave heating, by vapor deposition or gassing of the interior of the container and / or from the outside, as by admitting hot normal air.
• a gas sample G * is taken from the container according to FIG. 7b
• the test for explosive contaminations on the gas sample taken is preferably carried out before it is discharged or counteracted. if necessary, flame ionization is supplied to unit 41.
• the station then controls, for example, a valve 45, which unit 41 upstream.
• the gas to be tested is removed from one of the containers 71 on the conveyor 72, e.g. by venturi suction via a sealing connection 74.
• pump 76 carrier gas with container gas is fed to the measuring arrangement 78 with the discharge path.
• GS can be bridged and the arrangement 78 with pure carrier gas, e.g. cleaned air, are rinsed.
• pure carrier gas e.g. cleaned air

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• Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

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Publications (1)

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Citations (3)

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• 1990
  • 1990-12-06 DE DE4038994A patent/DE4038994C2/de not_active Expired - Fee Related
• 1991
  • 1991-12-04 EP EP92902467A patent/EP0514531A1/de not_active Withdrawn
  • 1991-12-04 BR BR919106215A patent/BR9106215A/pt not_active Application Discontinuation
  • 1991-12-04 JP JP4500239A patent/JPH05504411A/ja active Pending
  • 1991-12-04 AU AU89145/91A patent/AU8914591A/en not_active Abandoned
  • 1991-12-04 WO PCT/CH1991/000245 patent/WO1992010745A1/de not_active Application Discontinuation
  • 1991-12-04 CA CA002075034A patent/CA2075034A1/en not_active Abandoned
  • 1991-12-05 ZA ZA919595A patent/ZA919595B/xx unknown
  • 1991-12-05 MX MX9102404A patent/MX9102404A/es unknown
  • 1991-12-06 CN CN91112787A patent/CN1029530C/zh not_active Expired - Fee Related
• 1992
  • 1992-03-07 TW TW081101758A patent/TW226438B/zh active
  • 1992-08-06 FI FI923537A patent/FI923537A0/fi not_active Application Discontinuation

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